Intersection takeoffs. Get your sums right first

[Centaurus]

On 30 August 2016, a crew began takeoff from London Heathrow at an intersection one third of the way along the runway using the reduced thrust calculated for a full-length take off instead of the rated thrust calculated for the intersection takeoff. As a result, the aircraft was only just airborne as it crossed the airport boundary and an adjacent public road.

https://www.skybrary.aero/index.php/B773,_London_Heathrow_UK,_2016?utm_source=SKYbrary&utm_campaign=ce23019d24-614_Alarming_Story_31_12_2018_COPY_01&utm_medium=email&utm_term=0_e405169b04-ce23019d24-276530305 (https://www.skybrary.aero/index.php/B773,_London_Heathrow_UK,_2016?utm_source=SKYbrary&utm_campaign=ce23019d24-614_Alarming_Story_31_12_2018_COPY_01&utm_medium=email&utm_term=0_e405169b04-ce23019d24-276530305)

[mustafagander]

It's called situational awareness. It's all very well to have super duper EFB stuff but you need to know what questions you are asking it.

[Squawk7700]

A long time ago I was taxiing out at Albury to depart for Melbourne in a 4 seater with 2 POB.

I was following out a QantasLink Dash 8 and it was looking like it was going to take a while for them to get down the end of the runway and the controller suggested to me that I might like to do an intersection departure. I said sure thing, I'll take that. As I entered the runway to line-up, the controller said that there was now a 5 knot tailwind on that runway. I accepted and departed.... you can imagine what happened. It wasn't 5 knots, it was more like 10 and whilst I took off ok, it felt like the houses and factories weren't far below us. A few lessons learned that day!

[rog747]

A BA B777 at St Kitts mistook an intersection take off - They took the wrong intersection - They entered in error the one nearest the end of the runway - The a/c just got airborne - but it was very light on the short sector to Antigua iirc

[VH DSJ]

This is also a human factors issue. The FO actually got it right the first time when calculating the thrust setting and V speeds for the intersection departure but felt compelled to use the Captain's numbers even though his calculations were based on using the full length. Too steep a cockpit gradient, I think, and sadly, none of the 5 safety recommendations in the investigation report specifically addressed this.

[machtuk]

With todays technology & the ever increasing idea of removing the responsibility of the pilot thru so called clever assistance the smart boffins could introduce a voice warning based on the A/C's location (GPS) whist taxing to the Rwy the FMS has programed in it (full length in this case). If the A/C turns onto an intersection that is associated with the nominated Rwy & the thrust levers are advanced to a pre determined point a voice warning could be announced...."caution Intersection dept", part of the 'config' warning perhaps....? One could say....where does it all end? Anyway we are human, we are designed to make mistakes cause we have a brain that is not an exact science & influenced by a zillion different thought patterns, no amount of CRM or HF rubbish will ever remove it!

[Sunfish]

With todays technology & the ever increasing idea of removing the responsibility of the pilot thru so called clever assistance the smart boffins could introduce a voice warning based on the A/C's location (GPS) whist taxing to the Rwy the FMS has programed in it (full length in this case). If the A/C turns onto an intersection that is associated with the nominated Rwy & the thrust levers are advanced to a pre determined point a voice warning could be announced...."caution Intersection dept", part of the 'config' warning perhaps....? One could say....where does it all end? Anyway we are human, we are designed to make mistakes cause we have a brain that is not an exact science & influenced by a zillion different thought patterns, no amount of CRM or HF rubbish will ever remove it!

More things to go wrong. You would have to take into account DA, wind, weight and slope, so there is plenty to go wrong.

It hasnt happened to me in the air, but at sea I've experienced subtle system failures with magnetic, fluxgate and gyro compasses all reading different, GPS (two of them) different positions from the PC moving map software and the autopilot haywire. You've never experienced fear until all that integrated stuff starts acting up at once!

The option that worked for me was switch everything off, get out paper chart and pencil and hand bearing compass and Mk 1 eyeball.

I suggest pilots should be taught estimation and mental arithmetic instead of adding more electronic crutches.

Pilots should be able to answer this type of question : https://www.grc.nasa.gov/WWW/k-12/Numbers/Math/Mathematical_Thinking/fermis_piano_tuner.htm

[Capn Bloggs]

With todays technology & the ever increasing idea of removing the responsibility of the pilot thru so called clever assistance the smart boffins could introduce a voice warning based on the A/C's location (GPS) whist taxing to the Rwy the FMS has programed in it (full length in this case). If the A/C turns onto an intersection that is associated with the nominated Rwy & the thrust levers are advanced to a pre determined point a voice warning could be announced...."caution Intersection dept", part of the 'config' warning perhaps....?
I wouldn't have a problem with that. The FMS could be told what runway intersection was planned and bleat when the power went up too far at the wrong place. We have myriad protections doing this sort of thing now: takeoff config warnings, EGPWS, stick shakers. The challenge is keeping all the protections just out of sight so we can continue to fly without being hamstrung by silly SOPs leading to the Emirates prang at Dubai.

[Okihara]

Pilots should be able to answer this type of question : https://www.grc.nasa.gov/WWW/k-12/Numbers/Math/Mathematical_Thinking/fermis_piano_tuner.htm
If they were, they'd all be getting jobs in management consulting.

[compressor stall]

And although not strictly necessary with GPS, Airbus have recommended that the TO Shift is entered in the FMGC regardless for intersection departures for crew awareness to hopefully catch this trap.

[machtuk]

More things to go wrong. You would have to take into account DA, wind, weight and slope, so there is plenty to go wrong.

It hasnt happened to me in the air, but at sea I've experienced subtle system failures with magnetic, fluxgate and gyro compasses all reading different, GPS (two of them) different positions from the PC moving map software and the autopilot haywire. You've never experienced fear until all that integrated stuff starts acting up at once!

The option that worked for me was switch everything off, get out paper chart and pencil and hand bearing compass and Mk 1 eyeball.

I suggest pilots should be taught estimation and mental arithmetic instead of adding more electronic crutches.

Pilots should be able to answer this type of question : https://www.grc.nasa.gov/WWW/k-12/Numbers/Math/Mathematical_Thinking/fermis_piano_tuner.htm



Sunny what makes you think I haven't experienced that? I don't just fly GA ya know ! I thought you had had enuf & where leaving us?

[BEACH KING]

A long time ago I was taxiing out at Albury to depart for Melbourne in a 4 seater with 2 POB.

I was following out a QantasLink Dash 8 and it was looking like it was going to take a while for them to get down the end of the runway and the controller suggested to me that I might like to do an intersection departure. I said sure thing, I'll take that. As I entered the runway to line-up, the controller said that there was now a 5 knot tailwind on that runway. I accepted and departed.... you can imagine what happened. It wasn't 5 knots, it was more like 10 and whilst I took off ok, it felt like the houses and factories weren't far below us. A few lessons learned that day!
I well remember these words of wisdom my wise old instructor used to preach:

The most useless things in aviation are:
-The runway behind you
-The altitude above you
-The fuel in the bowser... and The only time you have too much fuel,.. is when you are on fire.

Your story with the departing Dash 8 and the effect of wind, reminds me of a time when I was taxiing for departure for an in-to wind takeoff. A Saab then gave an inbound call for a straight-in approach from the opposite end, with the wind blowing right up his arse.
As I waited for him at the holding point, the wind had picked up and was blowing a fair bit harder than the 10 knots of tailwind that the Unicom had advised him a couple minutes previously..and I told him so.
He acknowledged and continued with his approach and landing. The thing floated and floated until well past half runway and I was sure he would have to go-round...but he managed to stop with about 1 metre left. How he managed to turn around without running over the runway lights at the end was a feat in itself.
I complemented him on a fine downwind landing.

[Sunfish]

watched a cirrus try a downwind takeoff once, from a wet grass strip. There was only minor wing damage after the abort.

[Global Aviator]

Nothing wrong with intersection departures if calculated correctly.

I use them all the time if I can save time.

What continuously makes me laugh is seeing guys rush to an intersection departure only having to wait for one on final. What’s the point? The ole hurry up and wait. Sometimes I think it’s just a lack of airmanship.

[machtuk]

There's is a basic fix for this in 'most' cases. Do the sums on an appropriate intersection regards of the RWY available. Full length means extra margin, intersection (as calculated) means legal & safe:-) ATC often shuffle planes around to fit as many as possible off a certain Rwy, pays to be prepared like any boy scout:-):-)

[RodH]

The Airline I used to fly with in the late 80's had a rule : If pre start calculations had been made for a reduced thrust take off for a particular runway/ intersection and there is a runway change or different intersection offered after taxying and then any runway/ intersection departure change must be done with FULL thrust. Quite a sensible rule I reckon.

[Global Aviator]

With the EFB’s of today, how hard is it to recalculate the numbers?

Not hard!

Independently of course. What? Takes 2 mins??? (At a stretch).

[compressor stall]

The Airline I used to fly with in the late 80's had a rule : If pre start calculations had been made for a reduced thrust take off for a particular runway/ intersection and there is a runway change or different intersection offered after taxying and then any runway/ intersection departure change must be done with FULL thrust. Quite a sensible rule I reckon.

Interesting sentiment, but doesn't cover for a higher flap setting with the shorter runway.